ASTER-GDEM Topos of ASEAN, Malaysia, Thailand and the UK

[heckler]

Hi All

I couldn't find where to upload these maps. Check out the site this guy has done amazing work with the ASTER-GDEM data that was released last year. 10M contours.

http://maps.three15.org/node/12

He also has SRTM maps.

Pretty impressive and they are areas not on the main drop down lists.

The only issue seems to be that the maps are not transparent. Ok if you know your geo landmarks and don't rely on the roads.

Regards

[maps4gps]

I believe that site has been around for 3 or 4 years.

His example of an .mp file has transparency set to Y (yes).

He does not mention anything about modifiying the ASTER data to compensate for all the non-exsistent pits and peaks which are very common in the initial release of ASTER.

10m contours are about right for the gentler areas of the UK, but likely over-contoured for areas with high relief, especially for the SRTM data with a 90m spacing of elevation grid points. 

He is also using a 'non-standard' set of levels which may or may not create issues with the more standard level set.

To make a good contour mapset is very time consuming and involves more than simply acquiring the data and processing it.

It may be a good start with the data which is publicly available; however, I think his results are optismitic for the quality and scale of the source data.

[heckler]

What you say is probably true and as a newbie to all this, I'll take your word for it as I have no knowledge or understanding of how these these are put together. All I know is this is by far the best Thailand topo ma available. From what I know Garmin do not even offer a commercial map. On the trails I ride, I have not come across anything misleading so yep, a good start.

One thing on the transperancy, when I send the topo to my gps my base map is obscured.. I also tried to combine my Thailand road map with the topo using sendmap20 with the result not the expected one.

[maps4gps]

An overlay/transparent mapset should not obscure the basemap nor any other map being displayed - only exception would be any polygons in it will, which a mapset of contour lines would not need. 

I would bring the overlay/transparency issue to the attention of the map author.  He may have set it back to 'N' to make something else and forgot to change it to 'Y' before building the contours - done that myself.

I have only used SendMap for combining a few small files for test purposes.  Have you tried using MapSource and perhaps MapSetToolKit if the data is not MapSource ready?

Which GPSr are you using?

I would think it would be the best map of Thailand available.  It hard to better someone familiar with an area who can concentrate their efforts a an area or two.  The 10m contours in flat/gently sloping areas would be OK.  In steeply sloping/high relief areas using the SRTM data with a 90m grid spacing, I would expect parallel lines turning in unison as they went from one pair of grid points to the next.  Not very descriptive of the actual land surface and making for unnecessarly large file sizes.

[heckler]

Thanks. The map creator has not been active for awhile. Will try. Is the a way for the user to check the transperancy element?
I am using an eTrex Legend HCx.
How about the ASTER-GDEM data? Is it more accurate than the that provided by SRTM?

Thanks for this.

I have had a real issue with mapsource on my new vista machine. Will basecamp fill the place?

By the way, this is all helping me for my long saved and planned trip to Gunni and Crested Butte

[maps4gps]

You could use gpsmapedit to check the mapset properties.- http://www.geopainting.com/en/
Open the .img file - in the row of icons - fourth from left = Map Properties, then cgpsmapper - below midway down, the box for transparency should be checked.

ASTER is 30m grid spacing, SRTM is 90m.  ASTER is considered 'research grade' meaning you need to do a lot a research to determine the good versus bad data and modifications to make the data usable (not high quality to be used in research as that term was used 20 years ago).  

Many recent posts on issues with vista.  Basecamp will also work - get the latest version.

What are the geographic coordinates and size of the area you are interested in?